Low end torque

[Wally Knight]

Re: I'm trying

First let's go over the change to a 350. That alone will make more bottom end than messing with the heads.

To make this cost effective it assumes you are in the motor for a major rehab.

I don't know where people get the idea you can't undergrind a cast or steel crank. The mains come down around .200, part of that can be done on a lathe. The rod pins down from 2.100 to 2.00 and you can keep your small rods.

No internal mods to the block, 302/327/350 are all the same bore, 4.00. All that is different is the crank and pistons.

What you get is more cubes, more torque, that is what translate to seat of pants feel.

You can use a 350/350 cam and the damn thing will pull stumps and run like a scalded dog.

You want to help the heads, get rid of the undersize exhaust valve, put a 1.60 in with good valve seats, blend the bowls and let them go. There is more to had from the heads in the valve job than a novice with a die grider hacking up a set of heads.

[Wally Knight]

Re: I'm trying

First let's go over the change to a 350. That alone will make more bottom end than messing with the heads.

To make this cost effective it assumes you are in the motor for a major rehab.

I don't know where people get the idea you can't undergrind a cast or steel crank. The mains come down around .200, part of that can be done on a lathe. The rod pins down from 2.100 to 2.00 and you can keep your small rods.

No internal mods to the block, 302/327/350 are all the same bore, 4.00. All that is different is the crank and pistons.

What you get is more cubes, more torque, that is what translate to seat of pants feel.

You can use a 350/350 cam and the damn thing will pull stumps and run like a scalded dog.

You want to help the heads, get rid of the undersize exhaust valve, put a 1.60 in with good valve seats, blend the bowls and let them go. There is more to had from the heads in the valve job than a novice with a die grider hacking up a set of heads.

[Dale Pearman]

Re: Low end torque

I have just completed fitting an original 327 Corvette block (Ahem numbers & broach marks perfect) with a 3.625 4340 stroker crank. I left my heads alone with small valves and mechanically advanced the cam phasing by four degrees. I expect to remove stumps from the ground with this combination.

Dale.

[Dale Pearman]

Re: Low end torque

I have just completed fitting an original 327 Corvette block (Ahem numbers & broach marks perfect) with a 3.625 4340 stroker crank. I left my heads alone with small valves and mechanically advanced the cam phasing by four degrees. I expect to remove stumps from the ground with this combination.

Dale.

[Duke W.]

Re: I'm trying

The 929 cam is great for low end torque. I don't think you can beat it in that department. If you want a little more fire in the engine you could go with the L-79 cam. This will noticealbly improve the upper mid range and top end, but you will lose a bit of low end torque and the engine will idle at 750 to 800 with a bit of lope.

Duke

[Duke W.]

Re: I'm trying

The 929 cam is great for low end torque. I don't think you can beat it in that department. If you want a little more fire in the engine you could go with the L-79 cam. This will noticealbly improve the upper mid range and top end, but you will lose a bit of low end torque and the engine will idle at 750 to 800 with a bit of lope.

Duke

[Duke W.]

Journal overlap

The reason GM increased the journal size was to restore some of the journal overlap that would have been lost with the longer stroke and the smaller journals. It was not a bearing loading issue. Journal overlap is a key parameter that affects crankshaft stiffness.

Grinding down a 350 crank to the early journal sizes might work and last forever depending on how hard you run the engine, but be aware that on paper you loose some durability due to a less stiff crankshaft, and that's why GM increased the journal sizes.

Boring the main bearing saddles of a early small bearing block to accomodate the larger 350 crank mains would probably be a better way to install a 350 crank in a pre '68 block.

Duke

[Duke W.]

Journal overlap

The reason GM increased the journal size was to restore some of the journal overlap that would have been lost with the longer stroke and the smaller journals. It was not a bearing loading issue. Journal overlap is a key parameter that affects crankshaft stiffness.

Grinding down a 350 crank to the early journal sizes might work and last forever depending on how hard you run the engine, but be aware that on paper you loose some durability due to a less stiff crankshaft, and that's why GM increased the journal sizes.

Boring the main bearing saddles of a early small bearing block to accomodate the larger 350 crank mains would probably be a better way to install a 350 crank in a pre '68 block.

Duke

[Dale Pearman]

Re: Journal overlap

The bigger journals just increase bearing friction. Lots of drag race pros prefer small journals. I've enjoyed a life in the 7000 RPM range just fine with two bolt main, small journal engines.

I was once caught up in the "Build The Biggest Howitzer whether you need it or not" syndrome until the threat of bankruptcy loomed!

P.S. I like 22 caliber firearms as well.

Dale.

[Dale Pearman]

Re: Journal overlap

The bigger journals just increase bearing friction. Lots of drag race pros prefer small journals. I've enjoyed a life in the 7000 RPM range just fine with two bolt main, small journal engines.

I was once caught up in the "Build The Biggest Howitzer whether you need it or not" syndrome until the threat of bankruptcy loomed!

P.S. I like 22 caliber firearms as well.

Dale.

[Clem Z.]

Re: Journal overlap

NASCAR engines use honda size rod journals because they are 1.8885 dia which allows less friction and the weight of the rod big end and the crank pin is reduced so the counter weights can be made lighter which means it will rev faster.

[Clem Z.]

Re: Journal overlap

NASCAR engines use honda size rod journals because they are 1.8885 dia which allows less friction and the weight of the rod big end and the crank pin is reduced so the counter weights can be made lighter which means it will rev faster.